My understanding is that "espresso" is a word of Italian origin, but the French use the word "expresso" instead. Is there any reason for the difference in spelling, as many other languages have adopted the Italian spelling?

Actually, according to wikipedia:en, expresso is used in English, too.

Their notice is quite obivious, here it is.

The origin of the term "espresso" is the subject of considerable debate. Although some Anglo-American dictionaries simply refer to "pressed-out", "espresso," much like the English word "express", conveys the senses of "just for you" and "quickly," which can be related to the method of espresso preparation.

[...]

Many Latin European countries, such as France, use the expresso form. In the United States and Canada, the spelling espresso is widely considered correct while expresso appears as a less common variant or misspelling. Italy uses the term espresso, substituting most x letters in Latin root words with s; x is not considered part of the standard Italian alphabet.

"Expresso" may be used in English, but as Wikipedia says, it's a misspelling. People who write it are generally people who don't realize that "espresso" is the canonical and original spelling. In any case, I'm not sure it explains the French spelling.
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JefromiAug 27 '11 at 5:57